The utility model discloses a cigarette filter stick provided with a smoke diversion ball. At present, most smoke fast flows along the middle part of the filter stick in the filter stick, and little smoke disperses to the periphery, so that the filtering effect of a filament bundle is greatly reduced. The cigarette filter consists of a filament bundle core stick (1) and molding paper (2) which is wrapped at an outer layer, wherein an airtight ball (3) with the diameter size being 1/3-1/2 of the diameter of the filter stick is embedded in an axial lead of the filament bundle core stick (1). After mainstream smoke enters the filter stick, due to the diversion effect of the ball, a rectilinear flowing form of the smoke in a traditional filter stick is changed, so as to enable most smoke to disperse to the edge of the filter stick along the surface of the ball, and then partially flow to the center after a certain distance, so that the filament bundle of the whole filter stick is fully utilized, and the utilization rate of the filament bundle is effectively improved.